56 



LEHRBUCH DER BOTANIK FUR HOCHSCHULEN. 



because it, in a measure, recalls pliylogeny, the former because it 

 enables us to connect divergent forms. If, he goes on to say, we 

 are led on phylogenetic considerations to assume for a number of 

 different structures a common origin, we term their hypothetical 

 original form the "Grundform," while the derivatives of the 

 Grundform are its Metamorphoses. "Thereby the study of plant 

 metamorphoses, once only an ideal abstraction, is placed on a 

 true basis." We are somewhat afraid, however, that the student 

 who has perused the section will not feel quite happy about the 

 value of ontogeny as a guide to morphology, and will search it in 

 vain for many Grundforms. The paragraph on the "Ontogenie der 

 Pflanzen" will at any rate show how very little we do know of the 

 course of evolution or descent. 



We like the second chapter better than the first. Prof. Stras- 

 burger seems more at home in the internal morphology or histology 

 and anatomy, especially in treating of the cell and its contents, 

 though Protoplasm would have made a better starting-point than 

 the Cell. One cannot insist too strongly on the chambering of the 

 protoplasm in contradistinction to a mere cell theory, with the 

 unhappy bricks-in-a-w;ill illustration. However, we very soon come 

 to an excellent account of the vital substance, though one aspect is 

 not emphasised, namely, its action in the formation of substances 

 like aleuron and mucilage. Evidence has been brought to show 

 that these are the result of active secretion by the protoplasm, but 

 this is not indicated in the text. The expressive term coenocyte, 

 adopted by Dr. Vines for the multinuclear cells of the Siphonaceous 

 AlgsB and their fungal allies, is not retained, nor are the laticiferous 

 cells of Euphorbias mentioned in the same connection. We note 

 on p. 68 the revival of the theory of growth by intussusception as 

 necessary to explain many cases of growth of surface, as well as 

 the formation of centripetally developed wall-thickenings. 



In the discussion of tissue-systems we are glad to see the 

 adoption, as a basis, of the obvious arrangement into epidermis, 

 ground tissue, and vascular tissue ; an arrangement more easily 

 followed than one based on Van Tieghem's stele and its derivatives, 

 which, even supposing it to be generally true, is extremely difficult 

 for a student to understand and apply in his practical examination 

 of plant tissues. 



Physiology is considered under the following heads : — Physical 

 and vital properties ; the rigidity of the plant body ; nutrition ; 

 respiration; growth; movements; and reproduction. One or two 

 points call for remark. More evidence might have been adduced 

 for the action of the living cells in the wood tissue in the ascent of 

 the transpiration current ; while the account of assimilation of 

 carbonic acid gas, including the production of some form of carbo- 

 hydrate, is extremely crude, the return to the atmosphere of a 

 volume of oxygen equal to that of the carbonic acid gas absorbed 

 being explained (p. 169) by an equation which assumes the direct 

 formation of starch, viz., 6C0"^ + 5H2O = CgHioOs + 6O2. Not a 



Starch 

 word is said about recent investigations in the importance of some 

 form of sugar as one of the early results of such assimilation. 



